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the Box Presents… TeslaBox Stephen Bennett Devin Callahan Ben Kaslon Sushia Rahimizadeh Connor Shapiro
Team Watts in the Box Presents…
TeslaBoxStephen BennettDevin Callahan
Ben KaslonSushia Rahimizadeh
Connor Shapiro
Sushia Rahimizadeh
Overview Project Proposal and Purpose Hardware Design and Implementation
o Level 1 and 2 Block Diagrams Software Design and Implementation
o Use Case, System Context Diagram Division of Labor for Major Tasks Feasibility and Risks Economic Viability, Environmental Aspects,
Sustainability, Manufacturability, Safety, & Impact Schedule for the First Semester of Work Budget
Sushia Rahimizadeh
Proposal This project will consist of a scalable box or
drawer in which small hand-held devices or toys can be placed and wirelessly charged.
The box will require only an external source of power in order to be able to charge the devices.
The devices will perform all RF harvesting and charging automatically without user input.
The user simply opens the lid, places the devices inside, and shuts the lid. The devices do the rest.
Sushia Rahimizadeh
Purpose The purpose of this project is to demonstrate the
feasibility of scalable, commercially viable wireless charging.
It will be shown that any device is capable of being integrated with this technology and can be charged wirelessly in any station.o These stations can be placed in any household,
business, hotel room, etc. and can be of varying size.
Sushia Rahimizadeh
State of the Arto Heinrich Hertz – Directional, relatively high power free-
space power transmissiono Nikola Tesla – High power, omnidirectional power
transmissiono Jet Propulsion Laboratory and Raytheon (1973) -- 30 kW
transferred over 1.6 kmo Topic of “Wireless Power” has been of interest since
early 1900’s
Number of books that include the keyword “wireless power” since 1800, found by using Google Ngrams.
Sushia Rahimizadeh
Setup
Sushia Rahimizadeh
Background “Power Transmission”
o DC electrical power into RF powero RF power transmitted through space to some electrically
far pointo Power is collected and converted into DC power at this
point Multi-mode cavity
No field nulls
Field uniformity desired
Harvest power at any point within the cavity
Sushia Rahimizadeh
Expo Deliverables Hinged box
o Disables power transmission when openo Enclosed by conductive mesho Can mount all Tx antennas and display
RF Energy Transfero Uses antennas, not coupled inductorso High overall efficiency
• High conversion efficiency (DC RF, RF DC , DC DC)• Aperture-to-Aperture efficiency
Power Management Circuitso Supports Li-Ion and Ni-MH
Sushia Rahimizadeh
Expo Deliverables Externally-mounted display
o Unique device identificationo Power receivedo Remaining charge time
Hardware Design and
Implementation
Ben Kaslon
Overall System Block Diagram
Ben Kaslon
Overall System Block Diagram
Ben Kaslon
Power Transmit Circuit
Responsibility: o Converts supply power into a 1W 2.2 GHz RF
modulated signal
Ben KaslonVoltage-Controlled Oscillator
Responsibility: o Convert supply power to a 2.2 GHz signal
Design Goals: o This signal will be modulated tens of MHz around 2.2GHz
in order to improve power density uniformity in the box. o During development, input power is supplied from lab
bench DC supply, but final design will be supplied from standard wall outlet.
Voltage Controlled Oscillator: Crystek
CVCO55BE
Frequency Allocation Application Range (kHz) Min MaxVerizon and (at&T) 850 850Unused By Consumer Devices 850 1227.6L2 (Military GPS) 1227.6 1227.6L1 (Commercial GPS) 1575.4 1575.43G/4G 1700 1700Personal Communications Service 1900 1900Advanced Wireless Service 1915 1920Advanced Wireless Service 1995 2000Broadband Personal Communication 1850 1915Broadband Personal Communication 1930 19953G/4G 2100 2100Unused By Consumer Devices 2100 2400Wifi 2400 2400Bluetooth 2400 2480
2.2GHz was choseno Unallocated in
commercial spaceo No consumer wireless
devices will be harmed by this frequency coupling onto the devices
o Reduced component size
o Large availability of components operate at this frequency
Ben Kaslon
Power Amplifier Responsibility:
o Amplify 2.2GHz signal from the VCO to 1W Design Goal:
o Must be designed to make the transmitter circuit as efficient as possible.
Example Power Amplifier
Ben Kaslon
Transmit Antenna Responsibility:
o Transmits the amplified and modulated 2.2GHz signal Design Goal:
o Match Simulationso Display low loss to circuito Well matched to the operating frequencyo Widest bandwidth possible.
Ben Kaslon
Transmit Antenna Patch antenna will be used.
o Relatively easy to designo Small sizeo Low costo Can be etched directly into PCBo Lots of research available on design
Example Patch Antenna
Ben Kaslon
Ben KaslonPower Transmit Circuit Risks
Efficiency of the designed power amplifier too lowo If we are unable to design a sufficiently efficient
amplifier, a COTS amplifier will have to be usedo Ideally want 90% but will accept 50%
Design of the antenna does not match the simulations.o New simulations will have to be done with different,
more predictable substrates
Non-uniform field distribution in the cavityo Need to try a new modulation scheme
Ben Kaslon
Overall System Block Diagram
Ben Kaslon
Receiver Circuit
Receiving arbitrarily polarized radiation within the cavity
Rectifying received microwave power to DC power
Maintain optimal power transfer throughout
Ben Kaslon
Receive Antenna Responsibility:
o Receive microwave power
Design Goals:o Polarization diversityo Harmonic rejectiono Low reflections at fundamental frequency
Ben Kaslon
Matching Circuit Rectifier input impedance is a function of:
o Frequencyo Powero DC Loado Harmonic terminations
Responsibilities:o Ensuring optimal power transfer between antenna and
rectifier Design Goals:
o Achieve a low reflection coefficiento Low insertion losso A precise, common impedance
Ben Kaslon
Rectifier Responsibilities:
o Rectify microwave power to DC power
Design Goals:o Maximize rectification efficiencyo Low insertion losso High switching speedo Smaller devices (smaller junction capacitance).
Ben Kaslon
Receiver Circuit Risks Sub-Operational Efficiencies
o Increasing power transmitted into cavityo Antenna matching circuit redesign
Interference from deviceo Isolation will have to be introduced
Connor Shapiro
Overall System Block Diagram
Connor ShapiroPower Management Circuit
Design Goals:o Maximize boost converter efficiencyo Minimize microcontroller power consumption
Responsibilities: o Charge
controlling• Ni-MH• Li-Ion
o Battery monitoring• Generation of
UI/display data
Connor Shapiro
Power Management Circuit Risks Battery over-charging
o Prioritize cell protection
No power to turn on microcontroller – total system failureo Specialized cold-start circuit
Connor Shapiro
Battery Charging
Ni-MH Charge Cycleo Constant-Current
End-of-charge based on following peak V
Li-Ion Charge Cycleo Constant-Current &
Constant-Voltage End-of-charge based
end of current-draw
Connor Shapiro
Overall System Block Diagram
Connor Shapiro
Display Circuit
Antenna receives device status information
Microcontroller routine to translate data to generic display instructions
Connor Shapiro
Example LCD Displays Small compact LCD Display Designed to interface easily
with any MCU Can be used to display any
generic shapes Cycle through displaying data
for each device
Software Design and
Implementation
Stephen BennettSystem Context Diagram
Microcontroller TasksPower Manager
Rectified power detection Power management
o Control boost converter to produce correct battery charging profile
Monitor voltage and current going to chargeable device
Packetize power data and device ID for transmission to display circuit
Display Manager Decode power data
packets Convert received data
to appropriate display format
Stephen Bennett
Stephen Bennett
Display Responsibilities:
o Transceivers• Sending/receiving data at appropriate frequency• Outputting clean signal to microcontroller
o Microcontroller• Translating data to display instructions
o Display• Outputting data to user
Design Goals:o Display instructions are independent of received data
formato Displayed data is readable and user friendly
Microcontroller and Transceiver
MSP430 familyo Low costo Low powero Integrates well with CC1110o Prior experience
CC1110 Transceivero 315-915 MHzo Easy integration with
MSP430
CC430 familyo MSP430 with integrated
CC1110CC1110 Transceiver
MSP430 EVM
Stephen Bennett
Stephen Bennett
Software Risks Code rewrites due to changes in underlying
hardwareo Careful code design that is as hardware-independent as
possible
Code size exceeds space on microcontrollero Choose a microcontroller with more onboard memoryo Worst case – add external memory
Regressions or bugs created by new codeo Use a version control system (Git) in order to keep an
immutable code history
Administration
Devin Callahan
Division of Labor Sushia Rahimizadeh
o Research in energy harvesting, communications systems, and embedded systems
Ben Kaslono Antenna design with
a background in RF theory (Space Grant)
o Experience with VNA’s, SA’s and RF design software (NIST)
Devin Callahano Analog circuit
design, implementation, and control (LSI)
Stephen Bennetto Software background in embedded wireless
communications platform (Qualcomm)o Power management background (Space Grant)
Connor Shapiroo Power management background (TI & coursework)
Task SushiaStephe
n Ben Connor DevinProject Management Primary Seconda
rySeconda
ry
Construction of Box Secondary Tertiary Tertiary Tertiary Primary
Design of Tx Antenna Secondary Primary
Modulation of Signal Secondary Primary
Design of Power Amplifier Primary Seconda
ry
Design of Rectenna Secondary Primary Design of Power Converter Tertiary Secondary Primary TertiaryDesign of Microcontroller Circuit Primary Seconda
rySeconda
ryDisplay Circuit Seconda
ry Secondary Primary
Software Design Primary Tertiary Tertiary Secondary
Device Integration with System Seconda
ry Tertiary Primary
Devin Callahan
Feasibility Academic Resources
o Zoya Popovic – Faculty Advisor• Provide guidance in power amplifier and antenna design
o Steve Dunbar – Ph.D. Student• TI Analog/RF applications engineer willing to assist in
component selection and applications
o Sean Korhummel – Ph.D. Student• Provide guidance in converter design
Outside research already exists
Devin Callahan
Feasibility Most required components can be purchased
directly from electronics suppliers, including:o Voltage-controlled oscillatorso Microcontrollerso Power transistorso Converter inductors, diodes & capacitors
Devin Callahan
Economic Viability A household or business can purchase one of the
boxes
Any device outfitted with the charging hardware will be able to be charged in any box
Low cost to produce a unito Most cost found in the containero Relatively small cost for manufacturing of electronics
Devin Callahan
Sustainability Most parts are available commercially
o Voltage controlled oscillatoro Microcontrollero Peripheral parts
Parts that are not available commercially will designedo Need to be designed for efficiency
• Power amplifier• Rectifier• Antennas
o Cheap to produce Low maintenance expectations
o Unexpected component malfunction exempting
Devin Callahan
Manufacturability Main concern of the system is to ensure minimum
leak of RF power in compliance with FCC regulations
It will be easy to see if this project is working or not. Either the battery on the device will be charged or it will not
Component tolerances will not affect the design, apart from negligible detractions from system efficiency
Devin CallahanEnvironmental Considerations
Leaked power is chief concern o The system must abide by FCC regulations by emitting
no stray powero Also relates to overall efficiency
No other environmental concerns
Devin Callahan
Safety This system exhibits zero risk to the environment
or the population so long as all RF energy is kept within the box
A standard 120VAC outlet plug will eventually be used
Devin Callahan
Impact on Society Convenience
RF energy transfer proof-of-concept
Devin Callahan
Schedule
BudgetComponent CostPower Transmit Circuitry $300Receive Circuitry $50Power Management Circuitry
$220
Display Circuitry $225Software Debugger $100Box Construction $100Batteries $160Miscellaneous $100
Total $1255
Devin Callahan
Devin Callahan
Reach Goals Additional battery chemistries
More advanced GUI
USB Charging
Thank you!
Questions?
